This research is focused on using nitriding to enhance the wear resistance of austempered ductile iron (ADI), ductile iron (DI), and gray iron (GI). Three gas nitriding processes, namely "Gas nitriding + nitrogen cooled down to 800°F" (Blue), "Gas nitriding + cooled down to 300°F" (Gray), and "Gas nitriding + oil quenched" (Oil) were used. This study was carried out through optical metallography, roughness measurements, microhardness, and SEM. The ball-on-disc wear tests were conducted under lubricated conditions. It was found that COF for all materials in all nitrided conditions was small (<0.045). The best wear performance was seen for ADI processed using the Gray and Oil gas nitriding processes. These processes produced a compound layer thickness of 4-6μm, a low surface roughness (0.8-1.3 μm, Ra) and a high surface microhardness (1800-2200 HV). The wear rate decreased with increasing surface microhardness and decreasing surface roughness.
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